Methods, complexes, and system for forming metal-containing films

ABSTRACT

A method of forming a film on a substrate using Group III metal complexes. The complexes and methods are particularly suitable for the preparation of semiconductor structures using chemical vapor deposition techniques and systems.

This is a division of application Ser. No. 08/725,064, filed Oct. 2,1996, now U.S. Pat. No. 5,924,012, which is incorporated herein byreference.

FIELD OF THE INVENTION

This invention relates to methods and complexes for formingmetal-containing films, such as metal or metal alloy films, particularlyduring the manufacture of semiconductor structures. The complexesinclude a Group III metal, and are particularly suitable for use in achemical vapor deposition system.

BACKGROUND OF THE INVENTION

Aluminum is one of the three primary materials used today insemiconductor structures, the other two being silicon and silicondioxide. It is primarily used in thin films as an interconnect betweenthe specific structures formed on semiconductor substrates or substrateassemblies. Aluminum has been an important material in the fabricationof semiconductor structures because of its high conductivity, lowresistivity (2.7 μΩ-cm), high adherence to silicon and silicon dioxide,and low stress. And its use is expanding into other metallizationapplications. For example, it is being examined to replace tungsten incontacts or vias (i.e., very small openings located, for example,between surface conductive paths and or “wiring” and active devices onunderlying layers), which are getting narrower and deeper, and harder tofill with metal.

Aluminum alloys are also used in semiconductor structures, includingalloys of aluminum with copper, titanium, etc., and combinationsthereof. The addition of small quantities (typically, about 0.1-4%) ofother metals to aluminum improves the electromigration resistance andreduces the propensity of aluminum thin-films to form hillocks (i.e.,protrusions on the aluminum film surface). Such films, however, haveincreased resistivity over that of pure aluminum films.

In some applications, aluminum films are deposited using sputteringtechniques; however, sputtered aluminum is not effective at fillingcontacts or vias because of shoulders or overhangs that form at thecontact openings. These overhangs can lead to the formation ofkeyhole-shaped voids. Various collimation techniques help reduce thisproblem, but typically not enough to enable complete filling of verysmall geometries (e.g., less than about 0.5 μm). Therefore, it isdesirable to use chemical vapor deposition (CVD) to form aluminum andaluminum alloy films.

Dimethylaluminum hydride has emerged as one of the preferred materialsfor aluminum metallization by CVD. A serious problem with this material,however, is its pyrophoricity. This problem has been addressed to somedegree by the addition of amines to the compound to act as stabilizingLewis base donors to the aluminum center. However, such precursorcompounds are still pyrophoric, albeit to a lesser extent, and anadditional complicating factor is introduced into the vapor pressurebehavior of the precursor as a result of dissociation of the amine.Thus, there is a continuing need for methods and precursors for thedeposition of aluminum and aluminum alloy films, as well as other GroupIII metal or metal alloy films, on semiconductor structures,particularly using vapor deposition processes.

SUMMARY OF THE INVENTION

The present invention provides complexes and methods for formingmetal-containing films, particularly Group III metal-containing films onsubstrates, such as semiconductor substrates or substrate assembliesduring the manufacture of semiconductor structures. The method involvesforming a metal-containing film using a Group III metal complex,preferably a Group III metal hydride complex. The metal-containing filmcan be used in various metallization layers, particularly in multilevelinterconnects, in an integrated circuit structure.

The metal-containing film can be a single Group III metal, or a metalalloy containing a mixture of Group III metals or a Group III metal andone or more metals or metalloids from other groups in the PeriodicChart, such as copper, silicon, titanium, vanadium, niobium, molybdenum,tungsten, scandium, etc. Furthermore, for certain preferred embodiments,the metal-containing film can be a nitride, phosphide, arsenide,stibnide, or combination thereof. That is, the metal-containing film canbe a Group Ill-V (e.g., GaAs) semiconductor layer.

Thus, in the context of the present invention, the term “Group IIImetal-containing film” or simply “metal-containing film” includes, forexample, relatively pure films of aluminum, gallium, or indium, alloysof aluminum, gallium, and/or indium with or without other non-pnicogenmetals or metalloids, as well as complexes of these metals and alloyswith Group V elements (N, P, As, Sb) or mixtures thereof. The terms“single Group III metal film” or “Group III metal film” refer to filmsof aluminum, gallium, or indium, for example. The terms “Group III metalalloy film” or “metal alloy film” refers to films of aluminum, gallium,and/or indium alloys with or without other metals or metalloids, forexample. That is, if there are no metals or metalloids from groups inthe Periodic Chart other than Group III, the alloy films containcombinations of aluminum, gallium, and indium.

Preferably, the metal alloy films do not contain Group V metals ormetalloids (i.e., pnicogens).

One preferred method of the present invention involves forming a film ona substrate, such as a semiconductor substrate or substrate assemblyduring the manufacture of a semiconductor structure, by: providing asubstrate (preferably, a semiconductor substrate or substrate assembly);providing a precursor comprising one or more complexes of the formula:

M{[(C(R¹)₂)_(n)]_(x)N(R²)_(3−x)}(R³)_(y)(R⁴)_(z)  (Formula I)

wherein: M is a Group III metal; each R¹, R², R³, and R⁴ isindependently H or an organic group; x=1 to 3; n=1 to 6; y=1 when x=1and y=3−x when x=2 or 3; and z=3−x−y; and forming a metal-containingfilm from said precursor on a surface of the substrate (preferably, thesemiconductor substrate or substrate assembly). The metal-containingfilm is a Group III metal film or a Group III metal alloy film. Usingsuch methods the complexes of Formula I are converted in some manner(e.g., decomposed thermally) and deposited on a surface to form a GroupIII metal-containing film. Thus, the film is not simply a film of thecomplex of Formula I.

The complexes of Formula I are neutral complexes and may be liquids orsolids at room temperature. If they are solids, they are preferablysufficiently soluble in an organic solvent to allow for vaporization byflash vaporization, bubbling, microdroplet formation, etc. However,these complexes can also be vaporized or sublimed from the solid stateusing known chemical vapor deposition techniques.

Another method of the present invention involves forming a film on asubstrate, such as a semiconductor substrate or substrate assemblyduring the manufacture of a semiconductor structure, by: providing asubstrate (preferably, a semiconductor substrate or substrate assembly);providing a precursor comprising one or more hydride complexes of theformula:

M{[(C(R¹)₂)_(n)]_(x)(R²)_(3−x)}(R³)_(y)(R⁴)_(z)  (Formula I)

wherein: M is a Group III metal; each R¹, R², R³, and R⁴ isindependently H or an organic group with the proviso that at least oneof R³ and R⁴ is H; x=1 to 3; n=1 to 6; y=1 when x=1 and y=3−x when x=2or 3; and z=3−x−y; and forming a metal-containing film from saidprecursor on a surface of the substrate.

Yet another method of forming a metal-containing film on a substrate,such as a semiconductor substrate or substrate assembly during themanufacture of a semiconductor structure, by: providing a substrate(preferably, a semiconductor substrate or substrate assembly); providinga liquid precursor comprising one or more hydride complexes of theformula:

M{[(C(R¹)₂)_(n)]_(x)(R²)_(3−x)}(R³)_(y)(R⁴)_(z)  (Formula I)

wherein: M is a Group III metal; each R¹, R², R³, and R⁴ group isindependently H or a (C₁-C₃₀)organic group, with the proviso that atleast one of R³ and R⁴ is H; x=1 to 3; n=1 to 6; y=1 when x=1 and y=3−xwhen x=2 or 3; and z=3−x−y; vaporizing said liquid precursor to formvaporized precursor; and directing the vaporized precursor toward thesubstrate to form a metal-containing film on a surface of the substrate.

Thus, preferred embodiments of the methods of the present inventioninvolve the use of one or more chemical vapor deposition techniques,although this is not necessarily required. That is, for certainembodiments, sputtering, spin-on coating, etc., can be used.

The methods of the present invention are particularly well suited forforming films on a surface of a semiconductor substrate or substrateassembly, such as a silicon wafer, with or without layers or structuresformed thereon, used in forming integrated circuits. It is to beunderstood that the method of the present invention is not limited todeposition on silicon wafers; rather, other types of wafers (e.g.,gallium arsenide wafer, etc.) can be used as well. Also, the methods ofthe present invention can be used in silicon-on-insulator technology.Furthermore, substrates other than semiconductor substrates or substrateassemblies can be used in the method of the present invention. Theseinclude, for example, fibers, wires, etc. If the substrate is asemiconductor substrate or substrate assembly, the films can be formeddirectly on the lowest semiconductor surface of the substrate, or theycan be formed on any of a variety of the layers (i.e., surfaces) as in apatterned wafer, for example. Thus, the term “semiconductor substrate”refers to the base semiconductor layer, e.g., the lowest layer ofsilicon material in a wafer or a silicon layer deposited on anothermaterial such as silicon on sapphire. The term “semiconductor substrateassembly” refers to the semiconductor substrate having one or morelayers or structures formed thereon. The compounds of Formula Iincorporate features that make them selective for silicon over silicondioxide.

Also, the present invention provides a hydride complex of Formula Iwherein: M is a Group III metal (preferably Al, Ga, In); each R¹, R²,R³, and R⁴ group is independently H or an organic group, with theproviso that at least one of R³and R⁴ is H; x=1 to 3; n=1 to 6; y=1 whenx=1 and y=3−x when x=2or 3; and z=3−x−y.

A chemical vapor deposition system is also provided. The system includesa deposition chamber having a substrate positioned therein; a vesselcontaining a precursor comprising one or more complexes of Formula Iwherein M is a Group III metal, each R¹, R², R³, and R⁴ group isindependently H or an organic group, x=1 to 3, n=1 to 6, y=1 when x=1and y=3−x when x=2 or 3, and z=3−x−y; and a source of an inert carriergas for transferring the precursor to the chemical vapor depositionchamber.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional schematic of a semiconductor contact or viahaving an aluminum film deposited in accordance with the method of thepresent invention.

FIG. 2 is a schematic of a chemical vapor deposition system suitable foruse in the method of the present invention.

DETAILED DESCRIPTION

The present invention provides a method of forming a Group IIImetal-containing film using one or more Group III metal complexes,preferably a Group III metal hydride complex. These complexes aremononuclear (i.e., monomers in that they contain one metal permolecule). Preferred embodiments display few intermolecular forces ofattraction. Such complexes are generally volatile and transportable inthe gas phase. They preferably have vapor pressures sufficiently lowsuch that they are liquids at room temperature, although they can besolids. If they are solids, they are preferably soluble in organicsolvents, such as aromatic and aliphatic hydrocarbons, nitriles, ethers,amines, etc., which allows for vaporization as a homogeneous mixture bydirect liquid injection. They are also generally compatible with eachother, so that mixtures of variable quantities of the complexes will notinteract to significantly change their physical properties. Preferredembodiments are also generally nonpyrophoric.

Thus, many of the complexes described herein are suitable for use inchemical vapor deposition (CVD) techniques, such as flash vaporizationtechniques, bubbler techniques, and the microdroplet techniques.However, these complexes can also be vaporized or sublimed from thesolid state using other known CVD techniques. Preferred embodiments ofthe complexes described herein are particularly suitable for lowtemperature CVD, i.e., deposition techniques involving temperatures ofabout 50-200° C.

One preferred method of the present invention involves vaporizing aprecursor that includes one or more Group III metal complexes. Forcertain embodiments, the precursor can also include one or more Group Vcomplexes (i.e., a compound containing N, P, As, or Sb). Also, theprecursor can include complexes containing other metals or metalloids(preferably, non-pnicogen metals or metalloids).

The precursor can be vaporized in the presence of an inert carrier gasto form a relatively pure metal or metal alloy film. The inert carriergas is typically selected from the group consisting of nitrogen, helium,and argon. In the context of the present invention, an inert carrier gasis one that does not interfere with the formation of themetal-containing film. Whether done in the presence of a carrier gas ornot, the vaporization is preferably done in the absence of oxygen toavoid oxygen contamination of the films.

Alternatively, however, the precursor can be vaporized in the presenceof a reaction gas to form a film. The reaction gas can be selected froma wide variety of gases reactive with the complexes described herein, atleast at a surface under the conditions of chemical vapor deposition.Examples of reaction gases include oxygen, nitrous oxide, ammonia,silane, water vapor, hydrogen sulfide, hydrogen selenide, hydrogentelluride. Various combinations of carrier gases and/or reaction gasescan be used in the methods of the present invention to form metalcontaining films.

The Group III metal complexes described herein are four coordinatecomplexes having one multidentate ligand, which typically has at leastone carbon atom that covalently bonds to the metal and one nitrogen atomthat forms a dative bond with the metal. The designation “hydridecomplex” refers to a Group III metal complex containing at least onenegatively charged hydride ligand in addition to the multidentateligand. The multidentate ligand stabilizes the metal complex byincorporating the nitrogen donor atom into the ligand in such a way asto negate dissociation of the ligand prior to thermal decomposition.

The Group III metal complex is of the following formula:

M{[(C(R¹)₂)_(n)]_(x)(R²)_(3−x)}(R³)_(y)(R⁴)_(z)  (Formula I)

wherein: M is a Group III metal (preferably, Al, Ga, In); each R (i.e.,R¹, R², R³, R⁴) is independently H or an organic group (preferably, withthe proviso that at least one of R³ and R⁴is H); x=1 to 3; n=1 to 6; y=1when x=1 and y=3−x when x=2 or 3; and z=3−x−y. More preferably, R² is anorganic group and at least one of R³ and R⁴ is H. The ligand[(C(R¹)₂)_(n)]_(x)N(R²)_(3−x) can bond to the central metal through thenitrogen and at least one of the C(R¹)₂ units. The R³ and R⁴ groups canbe joined to form a ring or rings with the metal.

A preferred class of complexes of Formula I include hydride complexeswherein: M is a Group III metal (preferably, Al, Ga, In); each R (i.e.,R¹, R², R³, R⁴) is independently H or an organic group, with the provisothat at least one of R³ and R⁴ is H; x=1 to 3; n=1 to 6; y=1 when x=1and y=3−x when x=2 or 3; and z=3−x−y. For these hydride complexes, morepreferably, R² is an organic group. This class of complexes of Formula I(i.e., the hydrides) are particularly advantageous because additionalreducing equivalents are present in the complex (as a result of thehydride ligand(s)), which leads to less carbon contamination of thefilms formed upon decomposition of the complexes.

As used herein, the term “organic group” means a hydrocarbon group thatis classified as an aliphatic group, cyclic group, or combination ofaliphatic and cyclic groups (e.g., alkaryl and aralkyl groups). In thecontext of the present invention, the term “aliphatic group” means asaturated or unsaturated linear or branched hydrocarbon group. This termis used to encompass alkyl, alkenyl, and alkynyl groups, for example.The term “alkyl group” means a saturated linear or branched hydrocarbongroup including, for example, methyl, ethyl, isopropyl, t-butyl, heptyl,dodecyl, octadecyl, amyl, 2-ethylhexyl, and the like. The term “alkenylgroup” means an unsaturated, linear or branched hydrocarbon group withone or more carbon-carbon double bonds, such as a vinyl group. The term“alkynyl group” means an unsaturated, linear or branched hydrocarbongroup with one or more carbon-carbon triple bonds. The term “cyclicgroup” means a closed ring hydrocarbon group that is classified as analicyclic group, aromatic group, or heterocyclic group. The term“alicyclic group” means a cyclic hydrocarbon group having propertiesresembling those of aliphatic groups. The term “aromatic group” or “arylgroup” means a mono- or polynuclear aromatic hydrocarbon group. The term“heterocyclic group” means a closed ring hydrocarbon in which one ormore of the atoms in the ring is an element other than carbon (e.g.,nitrogen, oxygen, sulfur, etc.).

In metal complexes such as this, substitution is not only tolerated, butis often advisable. Thus, substitution is anticipated in the complexesof the present invention. As a means of simplifying the discussion andthe recitation of certain terminology used throughout this application,the terms “group” and “moiety” are used to differentiate betweenchemical species that allow for substitution or that may be substitutedand those that do not so allow or may not be so substituted. Thus, whenthe term “group” is used to describe a chemical substituent, thedescribed chemical material includes the unsubstituted group and thatgroup with nonperoxidic O, N, or S atoms, for example, in the chain aswell as carbonyl groups or other conventional substitution. Where theterm “moiety” is used to describe a chemical compound or substituent,only an unsubstituted chemical material is intended to be included. Forexample, the phrase “alkyl group” is intended to include not only pureopen chain saturated hydrocarbon alkyl substituents, such as methyl,ethyl, propyl, t-butyl, and the like, but also alkyl substituentsbearing further substituents known in the art, such as hydroxy, alkoxy,alkylsulfonyl, halogen atoms, cyano, nitro, amino, carboxyl, etc. Thus,“alkyl group” includes ether groups, haloalkyls, nitroalkyls,carboxyalkyls, hydroxyalkyls, sulfoalkyls, etc. On the other hand, thephrase “alkyl moiety” is limited to the inclusion of only pure openchain saturated hydrocarbon alkyl substituents, such as methyl, ethyl,propyl, t-butyl, and the like.

For the R groups (R¹, R², R³, and R⁴) in the complexes of Formula I, Hor (C₁-C₃₀)organic groups are preferred, H or (C₁-C₂₀)organic groups aremore preferred, and H or (C₁-C₈)organic groups are most preferred. Ofthe organic groups, nonaromatic groups (e.g., aliphatic groups andalicyclic groups, which may or may not include unsaturation, and whichmay or may not include heteroatoms such as N, O, S, P, Si, etc.) arepreferred. Of these, the aliphatic groups are more preferred, and alkylmoieties (particularly “lower” (C₁-C₄)alkyl moieties) are mostpreferred. The R³ and R⁴ groups can be joined to form a ring or rings.

Thus, the complexes of Formula I (wherein R¹=H, n=3, x=1, 2, or 3, R² isa lower alkyl moiety, and R³ and R⁴ are H or a lower alkyl moiety) cantake the following forms (which are representative only):

The complexes of Formula I are neutral complexes and may be liquids orsolids at room temperature. If they are solids, they are preferablysufficiently soluble in an organic solvent to allow for vaporization byflash vaporization, bubbling, microdroplet formation, etc. However,these complexes can also be vaporized or sublimed from the solid stateusing known chemical vapor deposition techniques.

Various combinations of the complexes described herein can be used inprecursors for chemical vapor deposition. Alternatively, certaincomplexes described herein can be used in other deposition techniques,such as sputtering, spin-on coating, and the like. Typically, thosecomplexes containing R groups with a low number of carbon atoms (e.g.,1-4 carbon atoms per R group) are suitable for use with vapor depositiontechniques. Those complexes containing R groups with a higher number ofcarbon atoms (e.g., 5-12 carbon atoms per R group) are generallysuitable for spin-on or dip coating. Preferably, however, chemical vapordeposition techniques are desired because they are more suitable fordeposition on semiconductor substrates or substrate assemblies,particularly in contact openings which are extremely small and requireconformally filled layers of metal.

For preparation of films containing Group Ill-V (e.g., GaAs)semiconductor materials, the precursors described herein contain one ormore complexes of Formula I and an appropriate source of the Group Velement. Such sources of Group V elements include compounds such as NH₃,PH₃, AsH₃, Me₃As, Me₃Sb, Me₃P, EtAsH₂, Me₂ ^(t)BuSb, etc.

For the preparation of alloy films, two or more complexes of Formula Ican be combined in a precursor mixture (e.g., AlH₂(CH₂CH₂CH₂NMe₂) andGaH₂(CH₂CH₂CH₂NMe₂) for an Al—Ga alloy). Alternatively, at least onecomplex of Formula I can be combined with another complex can becombined in a precursor mixture (e.g., AlH₂(CH₂CH₂CH₂NMe₂) and(Cu(PMe₃)(hfac) for an Al-Cu alloy).

The complexes of the present invention can be prepared by a variety ofmethods known to one of skill in the art. For example,AlH₂(CH₂CH₂CH₂NMe₂) can be prepared by reacting AlCl₃ withClMg(CH₂)₃NMe₂ followed by reduction.

As stated above, the use of the complexes of Formula I and methods offorming metal-containing films of the present invention are beneficialfor a wide variety of thin film applications in semiconductorstructures, particularly various metallization layers. For example, suchapplications include multilevel interconnects in an integrated circuitstructure. Typically, thin films of Group III metals, such as aluminum,and alloys thereof are deposited as polycrystalline materials, usuallyin the 0.5-1.5 μm thickness range.

A specific example of where a film formed from the complexes of thepresent invention would be useful is the structure shown in FIG. 1. Thesubstrate 16 may be in the form of an n-channel MOSFET (n-channelmetal-oxide semiconductor field-effect transistor), which may be used ina DRAM memory device. As shown, substrate 16 is a p-type silicon havingtwo n-type silicon islands 20 and 22, representing the transistor sourceand drain. Such a construction is well known. The gate for thetransistor is formed by a metal/polysilicon layer 24 deposited over asilicon dioxide layer 26. A relatively thick layer of an insulatingsilicon dioxide 28 overlies the active areas on substrate 16.

To connect the MOSFET with conductive paths on the surface of thedevice, contacts 30 and 32 have been etched through oxide layer 28 downto the surface of substrate 16. A metal or metal silicide layer 34, suchas titanium silicide, is deposited and formed at the base of contacts 30and 32. A thin, conformal barrier layer of a refractory metal nitride 36(e.g., titanium nitride, titanium aluminum nitride, titanium nitridesilicide) is deposited over the walls of the contacts. Because of thepresence of the conductive barrier layer, the electrical contact path isexcellent and the aluminum metal 38 which is deposited over therefractory metal nitride barrier layer is prevented from attacking thesubstrate surfaces.

The method of the present invention can be used to deposit ametal-containing film, preferably a metal or metal alloy film, on avariety of substrates, such as a semiconductor wafer (e.g., siliconwafer, gallium arsenide wafer, etc.), glass plate, etc., and on avariety of surfaces of the substrates, whether it be directly on thesubstrate itself or on a layer of material deposited on the substrate asin a semiconductor substrate assembly. The film is deposited uponthermal decomposition of a Group III metal complex that is preferablyeither liquid at the temperature of deposition or soluble in a suitablesolvent that is not detrimental to the substrate, other layers thereon,etc. Preferably, however, solvents are not used; rather, the Group IIImetal complexes are liquid and used neat. The method of the presentinvention preferably utilizes vapor deposition techniques, such as flashvaporization, bubbling, etc.

Conventional bubbler technology can be used to form films from thecomplexes of Formula I described above. In conventional bubblertechnology, a carrier gas, typically nitrogen, is bubbled through theprecursor (which is either a liquid or is dissolved in a liquid solvent)to sweep some of the precursor molecules into the processing chamber.

Alternatives to conventional bubbler technology include an approachwherein the precursor is heated and vapors are drawn off and controlledby a vapor mass flow controller. Further, another way is to pump the gasthrough the precursor using either a very precise metering pump or aliquid mass flow controller up to the point where it enters the reactionchamber. At that point, it can either be flash vaporized or injecteddirectly into a mixing chamber and showerhead where it is vaporized. Asdescribed in the article entitled, “Metalorganic Chemical VaporDeposition By Pulsed Liquid Injection Using An Ultrasonic Nozzle:Titanium Dioxide on Sapphire from Titanium (IV) Isopropoxide,” byVersteeg, et al., Journal of the American Ceramic Society, 78, 2763-2768(1995) a metalorganic CVD process utilizes pulsed on/off liquidinjection in conjunction with atomization by an ultrasonic,piezoelectrically driven nozzle to deliver such metalorganic precursors.The pulse injection is said to allow control of film deposition rates,as fine as monolayers per pulse. The ultrasonic nozzle provides a mistof droplets into the processing chamber of a reactor for reproduciblevaporization of the liquid precursor. Such a delivery system performsthe vaporization in the processing chamber.

The complexes of Formula I are particularly well suited for use withvapor deposition systems, as described in copending application U.S.Ser. No. 08/720,710 entitled “Method and Apparatus for Vaporizing LiquidPrecursors and System for Using Same,” filed on even date herewith.Generally, using the method described therein, the vaporization of aliquid precursor or precursor dissolved in a liquid medium is carriedout in two stages. First, the precursor is atomized or nebulizedgenerating high surface area microdroplets or mist. In the second stage,the constituents of the microdroplets or mist are vaporized by intimatemixture of the heated carrier gas. This two stage vaporization approachprovides a reproducible delivery for precursors (either liquid ordissolved in a liquid medium) and provides reasonable growth rates,particularly in device applications with small dimensions.

A typical chemical vapor deposition (CVD) system that can be used toperform the process of the present invention is shown in FIG. 2. Thesystem includes an enclosed chemical vapor deposition chamber 10, whichmay be a cold wall-type CVD reactor. As is conventional, the CVD processmay be carried out at pressures of from atmospheric pressure down toabout 10⁻³ torr, and preferably from about 1.0-0.1 torr. A vacuum may becreated in chamber 10 using turbo pump 12 and backing pump 14.

One or more substrates 16 (e.g., semiconductor substrates or substrateassemblies) are positioned in chamber 10. A constant nominal temperatureis established for the substrate, preferably at a temperature of about0-600° C., and more preferably at a temperature of about 50-300° C.Substrate 16 may be heated, for example, by an electrical resistanceheater 18 on which substrate 16 is mounted. Other known methods ofheating the substrate may also be utilized.

In this process, the precursor 40, which contains one or more complexesof Formula I, is stored in liquid form in vessel 42. A source 44 of asuitable inert gas is pumped into vessel 42 and bubbled through theliquid, picking up the precursor and carrying it into chamber 10 throughline 45 and gas distributor 46. Additional inert carrier gas may besupplied from source 48 as needed to provide the desired concentrationof precursor and regulate the uniformity of the deposition across thesurface of substrate 16. As shown, a series of valves 50-55 are openedand closed as required.

Generally, the precursor is pumped into the CVD chamber 10 at a flowrate of about 1-1000 sccm. The semiconductor substrate is exposed to theprecursor at a pressure of about 0.001-100 torr for a time of about0.01-100 minutes. In chamber 10, the precursor will form an adsorbedlayer on the surface of the refractory metal nitride 36. As thedeposition rate is temperature dependent, increasing the temperature ofthe substrate will increase the rate of deposition. Typical depositionrates are about 1000-10,000 Å/minute. The carrier gas containing theprecursor is terminated by closing valve 53.

Various combinations of carrier gases and/or reaction gases call be usedin certain methods of the present invention. They can be introduced intothe chemical vapor deposition chamber in a variety of manners, such asdirectly into the vaporization chamber, in combination with theprecursor, in combination (or in place of) the carrier gas.

The following examples are offered to further illustrate the variousspecific and preferred embodiments and techniques. It should beunderstood, however, that many variations and modifications may be madewhile remaining within the scope of the present invention.

EXAMPLES Example 1

Preparation of AlH₂(CH₂CH₂CH₂NMe₂)

AlCl₃ (2.0 g, 15 mmol) is added to a dry flask under an inert atmosphere(e.g., argon). To this is added 30 mL of hexanes, and the resultingslurry is cooled to −40° C. A solution of ClMgCH₂CH₂CH₂NMe₂ (30 mL of0.5 M in tetrahydrofuran) is added to the AlCl₃ over 10 minutes. Theresulting mixture is stirred for 18 hours. The solvent is then removedin vacuo, resulting in a white solid, which is dried in vacuo and thentransferred into a sublimator. A white sublimate of AlCl₂(CH₂CH₂CH₂NMe₂)is obtained at 100° C. and a pressure of 0.5 torr. This product (2.0 g,10.9 mmol) is dissolved in 30 mL of tetraethyleneglycol dimethylether(i.e., tetraglyme) and added to a suspension of LiAlH₄ (0.82 g, 21.8mmol) in 20 mL of tetraglyme. After stirring for several hours, theproduct AlH₂(CH₂CH₂CH₂NMe₂) is removed from the solvent by vacuumtransfer into a liquid nitrogen-cooled receiver. The resulting colorlessproduct is used for deposition of Al-containing films.

Example 2

Preparation of In(CH₃)₂(CH₂CH₂CH₂NMe₂)

This compound is prepared as described in Hostalek et al., Thin SolidFilms, 174, 1 (1989).

Example 3

Preparation of GaH(CH₃)(CH₂CH₂CH₂NMe₂)

GaCl₃ (2.0 g, 11.4 mmol) is added to a dry flask under an inertatmosphere (e.g., argon) and suspended in 25 niL of tetrahydrofuran. Tothis suspension is added 22.8 mL (11.4 mmol) of a 0.5 M solution ofClMgCH₂CH₂CH₂NMe₂ in tetrahydrofuran. The mixture is stirred for 18hours. The resulting solution is cooled to −60° C. and then 3.8 mL (11.4mmol) of a 3.0 M solution of MeMgBr in diethyl ether is slowly added.The mixture is allowed to warm to room temperature, and after 2 hoursthe solvent is removed in vacuo. The intermediate,GaCl(CH₃)(CH₂CH₂CH₂NMe₂), is then taken up in 30 mL of tetraglyme andadded dropwise to a suspension of LiAlH₄ (0.43 g, 11.4 mmol) in 20 mL oftetraglyme. After several hours, the product GaH(CH₃)(CH₂CH₂CH₂NMe₂) isremoved from the solvent by vacuum transfer into a liquidnitrogen-cooled receiver. The resulting colorless product is used fordeposition of Ga-containing films.

Example 4

Preparation of Aluminum Thin Films

A patterned semiconductor wafer is loaded into a CVD chamber, an d thewafer heated to approximately 250° C. The precursor,AlH₂(CH₂CH₂CH₂NMe₂), is loaded into a conventional stainless steelbubbler inside a glove box, and the bubbler transferred to the CVDsystem. A helium carrier gas flow of 50 sccm is established through thebubbler, and a chamber pressure of 0.25 torr is established. Thedeposition is carried out until a desired thickness of aluminum isobtained on the wafer.

The foregoing detailed description and examples have been given forclarity of understanding only. No unnecessary limitations are to beunderstood therefrom. The invention is not limited to the exact detailsshown and described, for variations obvious to one skilled in the artwill be included within the invention defined by the claims. Thecomplete disclosurer of all patents, patent documents, and publicationslisted herein are incorporated by reference, as if each wereindividually incorporated by reference.

What is claimed is:
 1. A hydride complex of the formula:M{[(C(R¹)₂)_(n)]N(R²)₂}(R³)(R⁴) wherein: (a) M is a Group III metal; (b)each R¹, R², R³, and R⁴ group is independently H or a(C₁-C₃₀)hydrocarbon group, with the proviso that at least one of R³ andR⁴ is H and none of the R groups are joined together to form ringsystems; and (c) n=1 to
 6. 2. The complex of claim 1 wherein M isselected from the group consisting of Al, Ga, and In.
 3. The complex ofclaim 1 wherein each R¹, R², R³, and R⁴ group is independently H or a(C₁-C₂₀) hydrocarbon group.
 4. The complex of claim 1 wherein each R¹,R², R³, and R⁴ group is independently H or a (C₁-C₄)alkyl moiety.
 5. Thecomplex of claim 1 wherein M is Al.
 6. The complex of claim 1 whereinR¹, R³, and R⁴ are each H, and R² is methyl.
 7. The complex of claim 5wherein R¹ and R³ are each H, and R² and R⁴ are each methyl.
 8. Thecomplex of claim 1 wherein M is Ga.
 9. The complex of claim 8 whereinR¹, R³, and R⁴ are each H, and R² is methyl.
 10. The complex of claim 8wherein R¹ and R³ are each H, and R² and R⁴ are each methyl.
 11. Thecomplex of claim 1 wherein M is In.
 12. The complex of claim 11 whereinR¹, R³, and R⁴ are each H, and R² is methyl.
 13. The complex of claim 11wherein R¹ and R³ are each H, and R² and R⁴ are each methyl.